The Toro Company of Minneapolis, Minnesota is the owner of U.S. Pat. Nos. 5,101,745 and 5,119,744. These patents disclose using high pressure water jets for soil cultivation. Namely, high pressure water jets are formed and injected directly into the ground from a movable implement that traverses over the ground. The high pressure jets form small holes or openings in the turf extending down to or below the root zone of the turf. These openings relieve soil compaction and allow water and other nutrients to reach and nourish the root zone of the turf, thereby generally promoting turf growth. The jets also fracture the soil to reduce overall soil density.
In the soil cultivation implement shown in these patents, a manifold is provided having a plurality of downwardly directed nozzles which point toward the ground. High pressure water applied to the manifold is formed into individual jets by the nozzles with the jets then being injected into the ground. The device includes a water supply means for periodically supplying high pressure water to the manifold to periodically create the water jets. The jets form an array of spaced holes in the turf as the implement travels over the ground.
While the water supply means shown in these prior Toro patents is effective for its intended purpose, it is relatively complex. It includes a mechanically driven pump having one or more reciprocating pump plungers which are driven back and forth in chambers to pump water at relatively high pressures, e.g. up to 5,000 psi. The high pressure water exiting the pump is received in an accumulator for use at those times when water injection is required. While the accumulator can be precharged by gas to about half the desired pressure, the incoming water from the pump raises the pressure of the accumulated liquid in the accumulator to the high pressures that are required. Finally, a valve periodically opens the outlet of the accumulator to supply a burst of high pressure water to the manifold. This valve is mechanically driven in a timed relationship to the implement's speed to allow proper spacing between the holes placed in the turf.
Three major components are required in the prior art water supply means just described, i.e. a high pressure, mechanically driven pump, a high pressure liquid accumulator, and a high pressure valve for periodically opening the outlet of the accumulator. All of these components have to withstand the high water pressures involved. The need for a plurality of separate components adds to the expense, complexity and weight of the soil cultivation apparatus.